The present invention relates to packages for storing and transporting sterile items, and more particularly, relates to a nested package for storing human or animal tissue specimens or medical devices in a moisture resistant, sterile environment.
Packages for storing items such as prosthetic medical implant devices and specimens of human or animal tissue are known in the art. Typically, prosthetic devices and human or animal tissue specimens are stored in packages until they are needed for transplant operations or for laboratory testing and analysis. Successful transplant operations or laboratory testing often turns, in part, on the sterility of the prosthetic device or tissue to be transplanted or tested. Indeed, it is well known in the art of transplant operations that the tissue to be transplanted must be kept in a sterile, bacteria free environment to avoid introducing microbial contaminants into the transplant recipient, which may lead to infections and other ailments.
Various packages for storing prosthetic implant devices, tissue specimens and other types of sterile items in a sterile environment have been proposed. For example, a typical package for a prosthetic implant device, such as a heart valve, comprises an inner package that fits into an outer package. The inner package has an open top and a recess to house the prosthetic device. To create a sterile environment, the prosthetic device is enclosed in the recess of the inner package by a cover sealed about the open top. Thereafter, the inner package is enclosed within a recess of the outer package by an outer lid sealed thereto. Variations of this type of package may include a holder retained with the inner tray to secure the prosthetic device for storage and shipment. A description of such packages can be found in greater detail in U.S. Pat. Nos. 5,720,391, 4,750,619, and 4,697,703, each of which is incorporated herein by reference.
Many packages commercially available in today""s market, including those represented by the foregoing patents, are inadequate to store human or animal tissue specimens in a moisture free environment. In particular, human tissue specimens include lipids, the fatty oils, waxes, sterols, and triglycerides that are stored forms of energy in living organisms. Often, human or animal tissue is stored in a dehydrated state, with most of the moisture of the tissue removed. However, even in a dehydrated state (for example, with less than or equal to 3% moisture), residual lipids may be present in the tissue.
The presence of residual lipids in the tissue specimen threaten the integrity of the seal of the packages in which the specimen is stored. For example, many of the packages used in today""s markets for storing medical devices include a container having a lid made from a porous, steam penetrable spun bonded polyolefin material, such as Tyvek available from Dupont DeNemours, having an adhesive coating. The porous material allows the package, together with the medical device enclosed therein, to be sterilized while in an assembled condition by forcing steam through the lids. However, when packages with lids made of porous material are used to store specimens of human or animal tissue, problems arise. In particular, the porous material acts as a sponge and actually begins to draw out and absorb the residual lipids that are present in the tissue being stored. Over time, the fatty oils associated with residual lipids that are absorbed by the porous material begins to dissolves the bond between the adhesive coating of the lid and the container of the package. As a result, the lid will begin to separate from the container, thereby exposing the dehydrated tissue specimen to moisture and microbial contaminants. The moisture is then absorbed by the tissue specimen which, over time, reduces the shelf-life or duration over which the tissue may be stored. Accordingly, packages having lids made of porous material suffer from an inability to prevent moisture uptake into the tissue specimen.
Various envelope packages have been proposed as a solution to the problem of storing human tissue specimens. A typical package for storing human tissue specimens is made of a double envelope comprising a sealed inner envelope for the specimen that is ultimately deposited and sealed in an outer envelope. Similarly, triple envelope packages have been also proposed. Triple packages include three sterilized envelopes, that is, an innermost envelope, an outermost envelope, and an intermediate envelope. The innermost envelope is made of plastic and stores the specimen. The innermost envelope is then stored in the intermediate envelope, also made of plastic material, and both envelopes are stored in the outermost envelope to complete the package. An example of a three-envelope package is described in greater detail in U.S. Pat. No. 5,257,692, which is incorporated herein by reference.
However, both the double and triple envelope packages described above are inadequate to store human tissue. Indeed, the envelope package shown in the ""692 patent is used to cryopreserve tissue specimens in a coolant medium, such as liquid nitrogen. As such, the structure and attributes of the package must be able to withstand extremely low temperature conditions and resist liquid nitrogen seepage, in order to accomplish the storage of human tissue specimens. Moreover most of the double or triple envelope packages commercially available are not concerned with preventing moisture uptake into the tissue. If the amount of moisture absorbed by the tissue specimen exceed acceptable regulatory standards for moisture, the shelf-life of the specimen would be violated.
Although human or animal tissue specimens may be packaged, stored and transported in glass bottles, packages of this sort suffer from several limitations. For instance, the specimens are typically vacuumed packed in an airtight glass containers. The glass containers are susceptible to becoming damaged during shipping and handling, which can lead to a loss of pressure or vacuum. As a result of a loss of pressure, the specimen may become exposed to moisture or microbial contaminants. As another limitation, the outer surface of the glass containers are often non-sterile. As such, the glass containers cannot be introduced into a sterile field, such as an operating room area. Moreover, the non-sterile outer surface of the glass containers creates a risk of contaminating the specimen when the package is opened and the specimen is removed. Furthermore, as an practical matter, the lids used to seal the glass packages are extremely difficult to remove because they must be secured to the bottle tightly to prevent microbial contaminants from attacking the specimen. The tightness of the lids becomes an inconvenience, particularly during a transplant operation, when quick access to the specimen to be transplanted is critical.
Accordingly, it is desired to provide a package for storing and transporting sterile items, particularly human or animal tissue specimens or medical devices, in a moisture resistant, sterile environment. It is also desired to provide a package that can store and transport human or animal tissue specimens under normal ambient temperatures or conditions. It is also desired to provide a package made of material that can be terminally sterilized (using gas,, radiation or other techniques) so that the package and its contents can be introduced into a sterile field. It is also desired to provide a package that is light-weight and easy to use.
The present invention relates to a moisture resistant package for storing and transporting sterile items, such as specimens of human or animal tissue or medical devices. The package comprises an inner tray that fits within a moisture and microbial contaminate resistant outer tray. The inner tray has a cavity for storing the specimen. The specimen is enclosed within the cavity by an inner lid made of nonporous material that is sealed to the inner tray by an adhesive. The nonporous material helps to prevent moisture uptake into the specimen. The inner tray is enclosed within a complementary shaped cavity of the outer tray by an outer lid sealed to the outer tray, thereby creating a moisture resistant, sterile environment.
In a preferred embodiment, both the inner tray and the outer tray are transparent so that the specimen can be viewed prior to opening the package. In addition, the inner lid may include at least one hole. The hole is provided to reduce the pressure differential that may occur between the ambient pressure of the cavity of the outer tray and the pressure within the cavity of the inner tray, which may otherwise cause premature lifting and separation of the inner lid from the inner tray.
In an alternative embodiment, the inner lid includes a tab that is folded over to overlie the inner lid when the package is closed. The tab automatically unfolds and springs away from the inner lid when the package is opened for easy grasping and removal of the inner tray from the outer tray.